Prevalence of clinical signs and examination-based DC/TMD diagnoses of temporomandibular disorders among residents of western Mongolia

Abstract

Background: Temporomandibular disorders (TMD) are the most common cause of non-dental orofacial pain and affect about one-third of adults. Population-based data obtained with standardized criteria are scarce in Mongolia, particularly outside the capital. Aim: To determine the prevalence of clinical signs of TMD and of examination-based Diagnostic Criteria for TMD (DC/ TMD) diagnoses among residents of western Mongolia, and to compare them by sex and age group. Materials and Methods: This retrospective secondary data analysis utilized research data collected in 2020–2021 across Bayan-Ulgii, Govi-Altai, Zavkhan, Uvs, and Khovd aimags. A total of 520 participants were included in the analysis; participants aged from 16 to 71 years, with females accounting for 72.3%. Ethical approval for the secondary use of data was obtained in 2024.Diagnoses that can be established from the examination alone (IIa, IIIa–IIIc) were assigned. Differences were tested with chi-square and Fisher’s exact tests and logistic regression. The study was approved by the MNUMS Research Ethics Committee (№24/3-06) Results: At least one clinical sign was found in 87.1% of participants; deviation on opening (58.1%) and joint sounds (56.2%) were the most common. Muscle and joint pain on opening were found in 16.7% and 18.3%, and muscle and joint pain on palpation in 8.7% and 8.3%, respectively. An examination-based diagnosis was established in 21.5% (95% CI 18.2–25.3); disc displacement with reduction (14.4%) was the most common and Group III diagnoses were found in 8.3%. Pain on palpation at three or more muscle sites was found in only 3.3%. Compared with men, women more often had joint pain on opening (21.0% vs 11.1%; p=0.009) and muscle and joint pain on palpation, and had 2.5-fold higher odds of a Group III diagnosis (OR 2.50; 95% CI 1.02–6.15). Muscle pain on opening decreased with age (from 26.7% to 10.6%; p=0.036), whereas diagnoses did not differ by age group. Conclusions: Most residents of western Mongolia had at least one clinical sign of TMD, mainly deviation on opening and joint sounds, and one in five had an examination-based DC/TMD diagnosis. Painful joint conditions were more common in women. The low prevalence of myofascial pain should be interpreted in light of limited standardization of palpation.